Lubricating oil composition for metal working

ABSTRACT

A lubricating oil composition for metal working, including a base oil composed of one or more selected from mineral oils and synthetic oils and having a kinematic viscosity at 40° C. of 50 to 300 mm 2 /s, and 0.01 to 10% by mass, based on the total amount of the composition, of a glycerin derivative (A) represented by general formula (I) 
     
       
         
         
             
             
         
       
     
     [wherein R 1  represents an alkyl group, alkenyl group or arylalkyl group, R 2  and R 3  each independently represent a hydrogen atom or a methyl group, A 1 O and A 2 O each independently represent an oxyalkylene group, n is 0, 1 or 2, p and q each represent the average number of added moles, and p+q is a value of 0 to 5] is used to provide a lubricating oil composition for metal working which can improve metal workability and suppress the generation of metal abrasion powder and surface damage when used in working of a metal or an alloy thereof, in particular, in deep drawing of a non-ferrous metal such as aluminum or an aluminum alloy and therefore enables the production of a product with high surface quality.

TECHNICAL FIELD

The present invention relates to a lubricating oil composition for metal working, and, more particularly, to a lubricating oil composition for metal working that can improve metal workability and reduce the generation of metal abrasion powder when used in plastic working, such as deep drawing, punching, wire drawing and cold forging, of a metal or an alloy thereof, in particular, a non-ferrous metal such as aluminum or an aluminum alloy, and enables the production of a product having high surface quality.

BACKGROUND ART

A lubricating oil composition for metal working that is used in metal working, such as drawing, of a metal or an alloy thereof, in particular, a non-ferrous metal such as aluminum or an aluminum alloy, is required to have an ability to improve the metal working performance, such as drawing performance, as a fundamental property from the standpoint of improving productivity. At the same time, the worked metal surfaces are required to have high quality. For example, the worked metal surfaces are required to be free from adhesion of abrasion powder and damages.

Conventionally, lubricating oils for metal working prepared by blending a mineral oil or synthetic hydrocarbon oil with an oily agent selected from alcohols, fatty acid esters and fatty acids have been used in drawing or deep drawing of a non-ferrous metal, such as aluminum or an aluminum alloy (refer to Patent Literatures 1 to 3, for example).

Patent Literature 1 discloses a lubricating oil composition for an aluminum alloy plate containing a polyalphaolefin, which is a polymer of a 1-alkene having a specific number of carbon atoms, and a fatty acid polyol ester (claim 1), and a deep drawing process using the lubricating oil composition (paragraphs [0052] and so on).

Patent Literature 2 discloses a lubricating oil composition for an aluminum alloy plate material containing a monoester having a specific number of carbon atoms and an oxo alcohol, and a press molding method using the lubricating oil composition (claims 1 and 6). In addition, a cupping experiment was conducted as a press molding experiment (paragraphs [0067] and so on).

Patent Literature 3 discloses a lubricating oil composition for use in working of an aluminum that contains an alcohol compound having 1 to 8 hydroxyl groups and 2 to 27 carbon atoms (claim 1), and its effects in a tapping experiment as a specific working process (paragraphs [0096] to [0102]).

In recent years, however, in the field of metal or metal alloy working, workability high enough to provide high dimensional accuracy with respect to the product design and to allow high-speed working for higher productivity is required.

In addition, with the increasing demand for metal products lighter in weight, higher in strength and smaller in size and thickness, the working conditions are becoming stricter and the generation of metal abrasion powder during working is increasing. As the generation of abrasion powder increases, the abrasion powder present between the tool and the material being worked is more likely to cause a decrease in dimensional accuracy of the product and, what is worse, to adversely affect the surface quality of the product.

For example, when a rectangular case for a lithium-ion battery is produced, a bottom perpendicular to side walls must be formed by deep drawing an aluminum or aluminum alloy plate using a rectangular punch having a rectangular cross-section. Such working requires high working performance. In addition, because the working must be performed over a long distance, the wear volume increases. Thus, abrasion powder adheres to the worked article and causes an increase of surface damage.

Under these circumstances, a lubricating oil composition for metal working that has a higher ability to improve metal workability and to prevent abrasion than conventional lubricating oil compositions for metal working is demanded.

CITATION LIST Patent Literature

Patent Literature 1: JP2008-274256 A

Patent Literature 2: JP2007-211100 A

Patent Literature 3: JP2010-184970 A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

The present invention has been made in view of the above circumstances, and it is, therefore, an object of the present invention to provide a lubricating oil composition for metal working which can improve metal workability and suppress the generation of metal abrasion powder and surface damage when used in working of a metal or an alloy thereof, in particular, in deep drawing of a non-ferrous metal such as aluminum or an aluminum alloy and therefore enables the production of a product with high surface quality.

Means for Solving the Problem

The present inventors conducted earnest studies to develop a lubricating oil composition for metal working having the preferred properties as described above, and, consequently, found that the object can be accomplished by using a lubricating oil composition obtained by blending a base oil having specific properties and composition and a glycerin derivative having a specific structure at a predetermined ratio. The present invention has been accomplished based on the finding.

The present invention provides:

(1) A lubricating oil composition for metal working, including a base oil composed of one or more selected from mineral oils and synthetic oils and having a kinematic viscosity at 40° C. of 50 to 300 mm²/s, and 0.01 to 10% by mass, based on the total amount of the composition, of a glycerin derivative (A) represented by general formula (I):

[wherein R¹ represents an alkyl group, alkenyl group or arylalkyl group, R² and R³ each independently represent a hydrogen atom or a methyl group, A¹O and A²O each independently represent an oxyalkylene group, n is 0, 1 or 2, p and q each represent the average number of added moles, and p+q is a value of 0 to 5], (2) The lubricating oil composition for metal working according to (1), having a kinematic viscosity at 40° C. of 80 to 260 mm²/s, (3) The lubricating oil composition for metal working according to (1) or (2), having a kinematic viscosity at 40° C. of 120 to 200 mm²/s, (4) The lubricating oil composition for metal working according to any one of (1) to (3), in which the base oil has a % C_(p) of 65 to 85, (5) The lubricating oil composition for metal working according to any one of (1) to (4), in which, in the glycerin derivative represented by general formula (I), R¹ is an alkyl group or alkenyl group having 12 to 24 carbon atoms, R² and R³ each are a hydrogen atom, n is 1, p=0 and q=0, (6) The lubricating oil composition for metal working according to any one of (1) to (5), further including 0.1 to 15% by mass of an oily agent, (7) The lubricating oil composition for metal working according to any one of (1) to (6), in which the metal working is deep drawing of an aluminum material or aluminum alloy material and (8) A method for deep drawing an aluminum material or aluminum alloy material at a drawing ratio of 1.5 or higher using the lubricating oil composition for metal working according to any one of (1) to (7).

Effect of the Invention

According to the present invention, it is possible to provide a lubricating oil composition for metal working which can improve metal workability and suppress the generation of metal abrasion powder and surface damage when used in working of a metal or an alloy thereof, in particular, in deep drawing of a non-ferrous metal and therefore enables the production of a product with high surface quality.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

A lubricating oil composition for metal working (which may be hereinafter referred to simply as “lubricating oil composition”) according to the present invention is a lubricating oil composition containing a base oil composed of one or more selected from mineral oils and synthetic oils and having a kinematic viscosity at 40° C. of 50 to 300 mm²/s, and a glycerin derivative having a specific structure.

[Base Oil]

The lubricating oil composition according to the present invention uses a base oil having a kinematic viscosity at 40° C. of 50 to 300 mm²/s.

When the kinematic viscosity at 40° C. is lower than 50 mm²/s, the thickness of the lubricating film that is formed between the material being worked and the die or punch during deep drawing will be too insufficient to provide necessary metal workability. On the other hand, while the thickness of the lubricating film will be greater and the working performance improves as the kinematic viscosity at 40° C. increases, the effect tend to be saturated or decrease and the lubricating oil composition is difficult to handle when the kinematic viscosity at 40° C. is higher than 300 mm²/s. This is not preferred. For these reasons, the base oil preferably has a kinematic viscosity at 40° C. of 60 mm²/s or higher, more preferably 80 mm²/s or higher, especially preferably 120 mm²/s or higher. As the kinematic viscosity at 40° C. of the base oil increases to 60 mm²/s or higher, to 80 mm²/s or higher and to 120 mm²/s or higher, the working performance improves.

The kinematic viscosity at 40° C. must be 300 mm²/s or lower, more preferably 280 mm²/s or lower, much more preferably 260 mm²/s or lower, especially preferably 200 mm²/s or lower.

The base oil used in the present invention preferably has a % C_(A), as measured by an n-d-M method, of 5 or lower and a % C_(p), as measured by an n-d-M method, of 65 or higher and 85 or lower. When the % C_(p) is 65 or higher, the base oil can have a desired viscosity index. When the % C_(p) is 85 or lower, a uniform and stable composition can be effectively obtained because the solubility of other base oils or additives in the base oil does not decrease.

The % C_(A) is more preferably 3 or lower, especially preferably 1 or lower. The % C_(p) is more preferably 70 or higher and 80 or lower.

The % C_(N) of the base oil, which is the balance excluding the % C_(A) and % C_(p), is preferably in the range of 10 or higher and 35 or lower.

The base oil used in the present invention preferably has a viscosity index of 70 or higher, more preferably 90 or higher, especially preferably 100 or higher. A base oil having a viscosity index of 70 or higher undergoes little change in viscosity with change in temperature and can exhibit lubricating properties over a wide range of temperature.

As the base oil used in the present invention, one or more selected from mineral oils and synthetic oils that satisfy the above property and composition requirements are used.

Various mineral oils can be used. Examples of the mineral oils include distillate oils obtained by atmospheric distillation of paraffinic crude oil, intermediate base crude oil or naphthene-base crude oil or by reduced-pressure distillation of atmospheric residue. The examples also include refined oils obtained by refining distillate oils by a commonly-used method, such as solvent-refined oils, hydrorefined oils, hydrocracked oils, dewaxed oils, and clay-treated oils. An oil obtained by hydroisomerization of slack wax can be also used.

Examples of the synthetic oils that can be used include poly-α-olefins having 8 to 14 carbon atoms, olefin copolymers (such as ethylene-propylene copolymer), branched olefins such as polybutene and polypropylene and hydrides thereof, ester compounds such as polyol esters (e.g., fatty acid esters of trimethylolpropane and fatty acid esters of pentaerythritol), and alkylbenzenes.

In the lubricating oil composition according to the present invention, the mineral oils may be used singly or in combination of two or more as the base oil, or the synthetic oils may be used singly or in combination of two or more. Alternatively, one or more of the mineral oils and one or more of the synthetic oils may be used in combination.

In the lubricating oil composition according to the present invention, a glycerin derivative represented by general formula (I) (which is hereinafter referred to as “component (A)”) is used as an additive:

The glycerin derivative as component (A) has the function of improving the ability to improve metal workability and suppressing the generation of abrasion powder.

In general formula (I), R¹ represents an alkyl group, alkenyl group or arylalkyl group. R² and R³ each independently represent a hydrogen atom or methyl group. A¹O and A²O each independently represent an oxyalkylene group. n is 0, 1 or 2, and p+q represents the average number of added moles and is a value of 0 to 5.

The alkyl group or alkenyl group represented by R¹ preferably has 12 to 18 carbon atoms, and may be straight, branched or cyclic. Examples include various types of dodecyl groups, tridecyl groups, tetradecyl groups, pentadecyl groups, hexadecyl groups and octadecyl groups, and various types of dodecenyl groups, tridecenyl groups, tetradecenyl groups, pentadecenyl groups, hexadecenyl groups and octadecenyl groups.

Examples of the arylalkyl group represented by R¹ include a benzyl group, a phenethyl group, a phenylpropyl group, a tolylmethyl group, a tolylethyl group, a xylylmethyl group and a xylylethyl group.

From the viewpoint of the above effects, R¹ is especially preferably an alkyl group or alkenyl group having 12 to 18 carbon atoms.

While R² and R³ each represent a hydrogen atom or methyl group, R² and R³ are preferably both a hydrogen atom in the present invention from the viewpoint of the above effects. While n is 0, 1 or 2, n is preferably 0 or 1 in the present invention from the viewpoint of the above effects.

When R² and R³ are both a hydrogen atom and n is 0, glycerin is used as a raw material of the glycerin derivative represented by general formula (I). When n is 1, diglycerin is used as the raw material. When n is 2, triglycerin is used as the raw material. In the present invention, n is preferably 0 or 1, that is, the use of glycerin or diglycerin is preferred.

A¹O and A²O each represent an oxyalkylene group. As the oxyalkylene group, an oxyethylene group and an oxypropylene group are preferred from the viewpoint of availability and the above effects. The above A¹O and A²O can be formed by adding an alkylene oxide to the hydroxyl groups of glycerin, diglycerin or triglycerin. As the alkylene oxide, ethylene oxide is especially preferred from the viewpoint of the above effects. Only one type of alkylene oxide may be used or two or more types of alkylene oxides may be used in combination. In other words, A¹O and A²O may be the same or different, and, when a plurality of A¹Os and a plurality of A²Os are present, the plurality of A¹Os may be the same or different and the plurality of A²Os may be the same or different.

In the present invention, p and q each represent the average number of added moles of the alkylene oxide, and p+q is a value in the range of 0 to 5. When the average number of added moles is greater than 5, the glycerin derivative has such a low solubility in the base oil that it cannot sufficiently function as the component (A). Preferably, p+q is 0, in other words, a glycerin derivative to which no alkylene oxide is added is preferred from the viewpoint of the above effects.

In the lubricating oil composition of the present invention, a monoalkyl or monoalkenyl ether of mono- or diglycerin represented by general formula (I-a) is preferably used as the glycerin derivative as the component (A):

[wherein R^(1a) represents an alkyl group or alkenyl group having 12 to 18 carbon atoms, and m represents 0 or 1].

Examples of the glycerin monoalkyl or monoalkenyl ether represented by general formula (I-a) include various types of glycerin monododecyl ethers such as glycerin monolauryl ether, various types of glycerin monotetradecyl ethers such as glycerin monomyristyl ether, various types of glycerin monohexadecyl ethers such as glycerin monopalmityl ether, various types of glycerin monooctadecyl ethers such as glycerin monostearyl ether, various types of glycerin monooctadecenyl ethers such as glycerin monooleyl ether, and compounds obtained by substituting the glycerin in these compounds with diglycerin.

Above all, a monoalkyl or monoalkenyl ether of diglycerin, in which case m in general formula (I-a) is 1, is especially preferably used.

The monoalkyl or monoalkenyl ether of mono- or diglycerin represented by general formula (I -a) can be prepared by a conventionally known method.

In the lubricating oil composition according to the present invention, the glycerin derivatives for the component (A) may be used singly or in combination of two or more. The content of the glycerin derivative (s) is selected from the range of 0.01 to 10% by mass based on the total amount of the composition. When the content is lower than 0.01% by mass, the above effects are not sufficiently obtained and the object of the present invention is therefore not accomplished. On the other hand, when the content is higher than 10% by mass, the solubility (uniformity) in the base oil may decrease, resulting in poor ability to improve metal workability and poor surface quality. The content of the component (A) is preferably 0.05 to 8% by mass, more preferably 0.1 to 5% by mass.

The lubricating oil composition according to the present invention preferably also contains an oily agent as a component (B). The oily agent used as the component (B) is not specifically limited, and any suitable substance selected from the substances conventionally used as oily agents in metalworking fluids may be used. Examples of the oily agent include alcohols, fatty acids and fatty acid esters.

Preferred examples of the alcohols include aliphatic saturated or unsaturated monohydric alcohols having 8 to 18 carbon atoms. The alcohol may be either straight or branched. Specific examples include straight or branched alcohols such as octanol, decanol, dodecanol, tetradecanol, hexadecanol, octadecanol, octenol, decenol, dodecenol, tetradecenol, hexadecenol and octadecenol.

Examples of the fatty acids include higher saturated or unsaturated fatty acids such as palmitic acid, stearic acid, isostearic acid, hydroxystearic acid, dimer acid, oleic acid and icosanoic acid.

Examples of the fatty acid esters include esters of an aliphatic carboxylic acid having 6 to 22 carbon atoms and an aliphatic alcohol having 1 to 18 carbon atoms. The aliphatic carboxylic acid having 6 to 22 carbon atoms may be a monobasic acid or a di- or polybasic acid, and may be either saturated or unsaturated. In addition, the aliphatic carboxylic acid may be either straight or branched. Examples of the aliphatic carboxylic acid include straight or branched aliphatic carboxylic acids such as octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, octadecanoic acid, hydroxyoctadecanoic acid, icosanoic acid, octenoic acid, decenoic acid, dodecenoic acid, tetradecenoic acid, hexadecenoic acid, octadecenoic acid, hydroxyoctadecenoic acid, icosenoic acid, octanedioic acid, decanedioic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, icosanedioic acid, octenedioic acid, decenedioic acid, dodecenedioic acid, tetradecenedioic acid, hexadecenedioic acid, octadecenedioic acid and icosenedioic acid.

The aliphatic alcohol having 1 to 18 carbon atoms may be either a monohydric alcohol or polyhydric alcohol, and may be either saturated or unsaturated. In addition, the aliphatic alcohol may be either straight or branched. Usually, a monohydric alcohol is used. Examples of the alcohol include methanol, ethanol, allyl alcohol, and straight or branched alcohols such as propanol, butanol, pentanol, hexanol, octanol, decanol, dodecanol, tetradecanol, hexadecanol, octadecanol, butenol, pentenol, hexenol, octenol, decenol, dodecenol, tetradecenol, hexadecenol and octadecenol. Above all, alcohols having 6 to 18 carbon atoms are preferred, and alcohols having 8 to 18 carbon atoms are more preferred.

In the lubricating oil composition according to the present invention, the oily agents for the component (B) may be used singly or in combination of two or more. The content of the oily agent(s) is preferably selected from the range of 0.1 to 15% by mass based on the total amount of the lubricating oil composition. When the content is in the above range, the component (B) acts in conjunction with the glycerin derivative as the component (A) to produce intended effects. The content is preferably 0.5 to 10% by mass, more preferably 1 to 8% by mass.

The lubricating oil composition according to the present invention may contain various additives, such as an extreme pressure agent, an antiwear agent, an antioxidant, an antirust, an anticorrosion agent, an antifoaming agent, a viscosity index improver and an antistatic agent, as needed as long as the object of the present invention is not impaired.

Examples of the extreme pressure agent include sulfur compounds such as sulfurized olefins, dialkyl polysulfides, diarylalkyl polysulfides and diaryl polysulfides, and phosphorus compounds such as phosphate esters, thiophosphate esters, phosphite esters, alkyl hydrogen phosphites, phosphate ester amine salts and phosphite ester amine salts. Examples of the antiwear agent include zinc dithiophosphate (ZnDTP), zinc dithiocarbamate (ZnDTC), molybdenum oxysulfide dithiophosphate (MoDTP) and molybdenum oxysulfide dithiocarbamate (MoDTC).

Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamines, phenyl-α-naphthylamines and alkylated α-naphthylamines, phenol-based antioxidants such as 2,6-di-t-butyl-p-cresol, and sulfur-based antioxidants such as 2,6-di-t-butyl-4-[4,6-bis(octylthio)-1,3,5-triazine-2-ylamino]phenol and dilauryl thiodipropionate.

Examples of the antirust and anticorrosion agent include sorbitan esters, neutral alkaline or alkaline-earth metal sulfonates, alkaline or alkaline-earth metal phenates, alkaline or alkaline-earth metal salicylates, thiadiazoles and benzotriazoles. Examples of the antifoaming agent include dimethylpolysiloxane and fluoroethers.

Examples of the viscosity index improver include polymethacrylates, dispersion-type polymethacrylates, and olefin-based copolymers (such as ethylene-propylene copolymer).

Preferred examples of the antistatic agent include non-metallic antistatic agents such as amine derivatives, succinic acid derivatives, poly(oxyalkylene)glycols and partial esters of polyhydric alcohols.

[Lubricating Oil Composition]

The lubricating oil composition according to the present invention preferably has a kinematic viscosity at 40° C. of 50 to 300 mm²/s, more preferably 60 to 280 mm²/s, much more preferably 80 to 260 mm²/s, especially preferably 120 to 200 mm²/s. When the kinematic viscosity at 40° C. is 50 mm²/s or higher, the lubricating oil composition can form a sufficient lubricating film and exhibit the function of improving the working performance when used in metal working such as deep drawing. When the kinematic viscosity at 40° C. is 300 mm²/s or lower, the lubricating oil composition is easy to handle.

The lubricating oil composition for metal working according to the present invention is suitably used in metal working, in particular, plastic working, such as deep drawing, punching, wire drawing and cold forging, of a metal or an alloy thereof. In particular, the lubricating oil composition can improve metal workability and reduce the generation of metal abrasion powder when used in deep drawing of non- ferrous metals such as aluminum and alloys thereof, and therefore enables the production of a product having high surface quality.

[Metal Working Method]

A metal working method according to the present invention is a method for deep drawing an aluminum material or aluminum alloy material using the lubricating oil composition for metal working. This deep drawing method can be carried out under severe working conditions. For example, the working can be carried out effectively at a drawing ratio of 1.5 or higher, such as 1.6 or higher and even 1.7 or higher.

EXAMPLES

While the present invention is next described in more details based on examples, the present invention is not limited to these examples.

A deep drawing experiment was conducted under the following conditions using the lubricating oil compositions for metal working obtained in the examples to evaluate their properties.

<Conditions for Deep Drawing Experiment> (1) Material to be Worked

Aluminum alloy: A3003-H24, a disk with a diameter of 70.00 mm and a thickness of 0.28 mm

(2) Test Device

Automatic universal sheet metal testing machine: Model USM-350D (manufactured by Tokyo Testing Machine)

Die: diameter=40.90 mm×R=5 mm

Punch: diameter=40.00 mm×R=4 mm

Clearance: 0.45 mm

Wrinkle suppressing force: 4.0 kN

Punch ascent rate: 20 mm/second (A high-speed testing unit was used)

Sample oil application method: 1 ml of oil was applied to each side of the material to be worked.

Drawing ratio: 1.75

<Evaluation Items>

(1) Maximum punch load (kN):

The workability of the product was evaluated. As the maximum punch load is lower, the material can be shaped at a lower load, in other words, the workability is higher and the productivity is higher.

(2) Generation of abrasion powder:

A surface of the product was wiped with a gauze pad, and the amount of black stain caused by abrasion powder was visually checked and evaluated according to the following evaluation criteria.

[Evaluation Criteria]

A: No black stain (abrasion powder) observed

B: Black stain observed (less than ⅓ of the surface (lateral surface) of the product)

C: Black stain observed (⅓ or more of the surface (lateral surface) of the product)

(3) Surface Damage:

The presence and extent of damage were visually checked and evaluated according to the following evaluation criteria.

[Evaluation Criteria]

A: No damage observed

B: Damage observed

Examples 1 to 7 and Comparative Examples 1 to 4

A lubricating oil composition for metal working having the composition shown in Table 1 was prepared and its properties were evaluated. The results are shown in Table 1.

TABLE 1 Example Comparative Example 1 2 3 4 5 6 7 1 2 3 4 Blend ratio Base oil A 98.0 98.0 98.0 95.0 98.0 98.0 98.0 in composition Base oil B 98.0 (% by mass) Base oil C 98.0 Base oil D 98.0 Base oil E 98.0 Glycerin derivative-I 2.0 5.0 2.0 2.0 2.0 2.0 Glycerin derivative-II 2.0 Glycerin derivative-III 2.0 Additive A 2.0 Additive B 2.0 Additive C 2.0 Evaluation Kinematic viscosity at 40° C. of composition (mm²/s) 127.3 129.4 131.2 125.9 88.5 254.6 195.7 11.3 123.4 123.5 126.7 results Maximum punch load (kN) 6.0 6.3 6.5 6.0 7.3 6.9 6.8 7.4 9.7 6.5 8.3 Amount of abrasion powder A A A A A A A C B C B Surface damage (scratches on lateral surfaces) A A A A A A A B B B B [Note] 1) Base oil A: hydrorefined mineral oil (kinematic viscosity at 40° C.: 130 mm²/s, % C_(P): 72.3, % C_(A): 0.0, % C_(N): 27.7, viscosity index: 107) 2) Base oil B: hydrorefined mineral oil (kinematic viscosity at 40° C.: 90 mm²/s, % C_(P): 72.0, % C_(A): 0.0, % C_(N): 28.0, viscosity index: 107) 3) Base oil C: hydrorefined mineral oil (kinematic viscosity at 40° C.: 260 mm²/s, % C_(P): 72.7, % C_(A): 0.0, % C_(N): 27.3, viscosity index: 107) 4) Base oil D: hydrorefined mineral oil (kinematic viscosity at 40° C.: 200 mm²/s, % C_(P): 72.6, % C_(A): 0.0, % C_(N): 27.4, viscosity index: 107) 5) Base oil E: hydrorefined mineral oil (kinematic viscosity at 40° C.: 12 mm²/s, % C_(P): 76.2, % C_(A): 0.4, % C_(N): 23.4, viscosity index: 114) 6) Glycerin derivative-I: diglycerin monooleyl ether 7) Glycerin derivative-II: monoglycerin monooleyl ether 8) Glycerin derivative-III: monooleic acid POE (2) glyceryl 9) Additive A: oleyl alcohol 10) Additive B: oleic acid 11) Additive C: trimethylolpropane trioleate

As can be understood from Table 1, the lubricating oil compositions for metal working according to the present invention (Examples 1 to 8) required as low a maximum punch load as 7.3 kN or lower. This means the lubricating oil compositions can improve metal workability. In addition, neither abrasion powder nor surface damage was observed. This also means that the lubricating oil compositions can improve metal workability.

In contrast, the lubricating oil composition of Comparative Example 1 using the base oil E, which does not satisfy the kinematic viscosity requirement (kinematic viscosity at 40° C.: 12 mm²/s), required higher maximum punch load (7.4 kN) compared to the lubricating oil composition of Example 1 using the base oil A (130 mm²/s), and showed poor results regarding the abrasion powder and the surface damage. None of the lubricating oil compositions of Comparative Examples 2 to 4, which contain any one of the oily agent A to C instead of the glycerin derivative of the present invention, showed satisfactory results regarding the maximum punch load, the abrasion powder amount and the surface damage. This means that the lubricating oil compositions are inferior in the ability to improve metal workability.

INDUSTRIAL APPLICABILITY

The lubricating oil composition for metal working according to the present invention can improve metal workability and suppress the generation of metal abrasion powder when used in metal working of a non-ferrous metal such as aluminum, in particular, deep drawing of aluminum or an aluminum alloy and therefore enables the production of a product with high surface quality. 

1. A lubricating oil composition for metal working, comprising at least one base oil selected from a mineral oil and a synthetic oil, said base oil having a kinematic viscosity at 40° C. of from 50 to 300 mm²/s, and from 0.01 to 10% by mass, based on the total amount of the composition, of a glycerin derivative (A) represented by general formula (I):

wherein R¹ represents an alkyl group, alkenyl group or arylalkyl group, R² and R³ each independently represent a hydrogen atom or a methyl group, A¹O and A²O each independently represent an oxyalkylene group, n is 0, 1 or 2, p and q each represent the average number of added moles, and p+q is a value of from 0 to
 5. 2. The lubricating oil composition for metal working according to claim 1, wherein the kinematic viscosity of the base oil at 40° C. is from 80 to 260 mm²/s.
 3. The lubricating oil composition for metal working according to claim 1, wherein the kinematic viscosity of the base oil at 40° C. is from 120 to 200 mm²/s.
 4. The lubricating oil composition for metal working according to claim 1, wherein the base oil has a % C_(p) of from 65 to
 85. 5. The lubricating oil composition for metal working according to claim 1, wherein R¹ is an alkyl group or alkenyl group having from 12 to 24 carbon atoms, R² and R³ each are a hydrogen atom, n is 1, p=0 and q=0.
 6. The lubricating oil composition for metal working according to claim 1, further comprising from 0.1 to 15% by mass of an oily agent.
 7. The lubricating oil composition for metal working according to claim 1, wherein the metal working is deep drawing of an aluminum material or aluminum alloy material.
 8. A method for deep drawing an aluminum material or aluminum alloy material at a drawing ratio of 1.5 or higher, said method comprising applying the lubricating oil composition for metal working of claim
 1. 9. The lubricating oil composition for metal working according to claim 6, wherein the oily agent is an alcohol, a fatty acid, a fatty acid ester or a mixture thereof.
 10. The lubricating oil composition for metal working according to claim 1, further comprising one or more selected from an extreme pressure agent, an antiwear agent, an antioxidant, an antirust, an anticorrosion agent, an antifoaming agent, a viscosity index improver and an antistatic agent.
 11. A method for deep drawing an aluminum material or aluminum alloy material at a drawing ratio of 1.7 or higher, said method comprising applying the lubricating oil composition for metal working of claim
 1. 12. The lubricating oil composition for metal working according to claim 1, wherein the kinematic viscosity of the lubricating oil at 40° C. is from 80 to 260 mm²/s.
 13. The lubricating oil composition for metal working according to claim 1, wherein the kinematic viscosity of the lubricating oil at 40° C. is from 120 to 200 mm²/s. 